1. Field of the Invention The present invention relates to a joint. For instance, the present invention relates to a joint provided therein with a pipe functional component such as a diaphragm valve.
2. Description of Related Art
Diaphragm valves are often used in semiconductor manufacture apparatuses for controlling a supply of various gases.
The diaphragm valves include a valve unit for opening/closing a flow channel, a drive unit for driving the valve unit and a diaphragm interposed between the valve unit and the drive unit to insulate the valve unit from the drive unit. The diaphragm keeps the fluid flowing in the flow channel from entering the drive unit and simultaneously keeps metal particles and the like of the drive unit from being mixed in the fluid.
For instance, Literature 1 (JP-A-9-14470) and Literature 2 (JP-U-7-19673) disclose diaphragm valves that include: a valve body; an inflow channel and an outflow channel provided to the valve body; a valve seat provided between the inflow channel and the outflow channel; a diaphragm that is into and out of contact with the valve seat to open/close a gap between the inflow channel and the outflow channel; a valve shaft screwed to a side of the valve body opposite to the valve seat with the diaphragm being interposed, the valve shaft being axially moved to bring the diaphragm into/out of contact with the valve seat; and a handle integrated with the valve shaft.
Further, Literature 3 (JP-A-2000-179744) discloses a bellows valve (not a diaphragm valve) of which a valve shaft (spindle) is provided with a triple thread screw. In the bellows valve, turning of a handle provided to the valve shaft causes a movement of a square tube screwed to the valve shaft by the triple thread screw, so that the bellows valve is opened/closed by a valve element integrated with the square tube. With the use of the triple thread screw, the bellows valve is capable of causing a larger movement of the valve element per a rotation of the handle, thereby enabling open/close operation with a small operation amount. Such a multiple thread screw is effectively employed for enhancing operability in bellows valves that have considerably larger stroke of the valve element than that of diaphragm valves.
However, the diaphragm valves disclosed in Literatures 1 and 2 include a block-shaped valve case (respectively shown as reference sign 1) and is supported by a component different from a pipeline via an appropriate support member attached to the valve case. Since the support member is screwed to the valve case, the valve case has to be sufficiently thick for providing a threaded hole. Thus, the size and weight of such a valve case are increased, which hampers size and weight reduction of the diaphragm valve.
In addition, the diaphragm valves disclosed in Literatures 1 and 2 require a long valve shaft and a large number of components including a housing with which the valve shaft is screwed, a cylindrical nut to be screwed with the housing, the valve case with which a cylindrical nut is screwed and a lock nut for keeping the cylindrical nut from being loosened, which also hampers the size and weight reduction of the diaphragm valve.
Further, a pipeline connected to a diaphragm valve for relatively small flow amount of reaction gas (e.g. a diaphragm valve used for a semiconductor manufacture apparatus) has not so large a pipe diameter and has small rigidity. Thus, though a screw portion is provided to each of right and left joint portions of the diaphragm valves disclosed in Literatures 1 and 2, sufficient support strength cannot be obtained even when the diaphragm valves are to be supported between ends of pipelines by connectors screwed to the screw portions. Accordingly, as described above, it is necessary to provide a large valve case to the diaphragm valves to support the diaphragm valves via support members screwed to the valve case. The provision of the support member results in a complicated support structure.
The above applies not only to diaphragm valves but also to pipe functional components in general including various valves such as a small-flow-amount check valve, a branch valve, a relief valve, a ball valve and a bellows valve, and a filter.
In other words, these pipe functional components not only include a large-size valve case and a number of components that hamper size and weight reduction, but also are supported at a part different from a pipeline via a complicated support structure. Accordingly, in order to independently provide the pipe functional components at predetermined sections, the pipe functional components that are relatively larger than the pipeline are noticeably present in a pipe system, resulting in a complicated impression of the pipe system.
Incidentally, though the bellows valve disclosed in Literature 3 can reduce the operation amount of the handle and exhibits excellent operability, the size of the valve shaft and the square tube cannot be reduced.
The bellows valve is generally used for a larger amount of fluid as compared to a diaphragm valve and has flanges on both ends of a joint portion thereof. In order to accept a large amount of fluid, the diameter of the pipeline and, consequently, rigidity thereof are increased. Thus, when the flange of the bellows valve is fixed to a flange of the pipeline to support the entirety of the bellow valve, a sufficient support strength can be ensured.
In other words, the pipe functional components for a large flow amount are typically not adapted for reducing the size and weight, and even when the pipe functional components are disposed in a pipe system, such pipe functional components are buried in the large complicated pipelines, which does not provide so much complicated impression.